Propargylation aldehydes/ketones

Bohlmann (207) reported the reaction of /I -dehydroquinolizidine with methyl vinyl ketone and with propargyl aldehyde forming a partially saturated derivative of julolidine 135 and julolidine (136), respectively. Compound 135 can be prepared also by mercuric acetate dehydrogenation of ketone 137, which is formed by condensation of 1-bromoethylquinolizi-dine with ethyl acetoacetate (Scheme 11). 

Cyanohydrin diethyl phosphates 87, easily accessible from propargyl aldehydes or ketones of type 86, reacted with lithium dialkylcuprates or similar reagents via an Sn2 process to give cyanoallenes in moderate to good yields [135]. The transformations 80 —> 81 and 84 —> 85 are only formally also SN2 reactions. Thus, plausible catalytic cycles, which include different short-lived palladium intermediates, have been postulated to explain these nucleophilic substitution reactions [127, 134],... 

Alkynyl ketones can be prepared using the former useful methodology. Starting from propargyl aldehyde diethyl acetals and benzotriazole under toluene reflux, l-(benzotriazol-1-yl) propargyl ethyl ethers were prepared in 83-84% yield. The deprotonation is very... 

Hydrolysis yields the terminal acetylene (3) carbonation yields the propargylic acid (4). Synthesis of a wide variety of acetylenes is possible by the reaction of the intermediate lithium acetylides with other electrophiles (alkyl halides, aldehydes, ketones). 

Conjugated yne-2-ynylidene 1,3-dithioles 228 were synthesized via Wittig reactions of phosphonium salts 225 with 3-phenyl-substituted propargyl aldehydes 227 (R = H, = Ph). Diaryl-substituted derivatives 228 were prepared in Horner-Wittig reactions of phosphonates 226 with ketones 225 (R =R = Ph or -02NC6H4) (Equation 13) <2004CL1190>. 

C=CHCH2NAtN=CR has been reported. " Propargylic vinylic compounds give allenic aldehydes, ketones, esters, or amides ... 

This chapter focuses the attention on the reactions of nonstabilized carbanionic compounds such as alkyl, vinyl, aryl, alkynyl metals, etc., and the chemistry of the stabilized system, i.e. allylic, propargylic or oxaallylic carbanions is presented in Volume 2 of this series. Electrophiles with C=X bonite which are discussed include aldehydes, ketones, epoxides, aziridines, acetals, orthoesters and imines, all of which turn into highly reactive electrophiles in the presence of Lewis acids. 

Reduction of Cp2TiCl2 with Mg in the presence of propargyl acetates gives allenyl Ti intermediates which react with nucleophilic reagents such as aldehydes, ketones, acetonitrile, and allyl bromide to give carbon-carbon bondforming products in moderate yields.1149... 

Pyrazole itself can be formed by the reaction of hydrazine with propargyl aldehyde. Using p-chloro-," P-alkoxy-" p-amino-" -enones as 1,3-dicarbonyl synthons are other ways to influence the regiochemistry of reaction." 2-(Dimethoxymethyl)-ketones react with arylhydrazines at the ketonic carbonyl, thus reversing the intrinsic reactivity of a p-keto-aldehyde." ... 

General. Reduces most groups aldehydes, ketones, acids and acid derivatives, nitriles, aliphatic nitro, halides and propargyl alcohols... 

Oxidation of Propargylic Alcohols. Propargylic alcohols are easily oxidized by Mn02 to alkynic aldehydes and ketones (eqs 16-18). In the example in eq 19 the unstable propargyl aldehyde is trapped as a Michael adduct. ... 

Alkyne replacements have also been reported. In 2008, Sakai et al. described the use of alkynylsilanes instead of terminal alkynes in the Cu-catalyzed synthesis of propargyl-amines, which was applicable to both secondary and primary aliphatic amines, although the latter afforded the corresponding products in low yield [145]. Very recently. Van der Eycken et al. applied the A -coupling to the C—H alkylation of azoles through a copper-catalyzed hetero-arene-amine-aldehyde/ketone coupling [146]. This reaction is proposed to proceed through the initial condensation of... 

Ye, L., and Zhang, L. (2009). Practical s3Tithesis of linear a-iodo/bromo-a, p-unsaturated aldehydes/ ketones from propargylic alcohols via Au/Mo bimetallic catalysis. Org. Lett., 11, 3646-3649. 

When X=OH, this conversion of acetylenic alcohols to unsaturated aldehydes or ketones is called the Meyer-Schuster rearrangement The propargyl rearrangement can also go the other way that is, 1-haloalkenes, treated with organocopper compounds, give alkynes. ... 

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